Coil for arc-lamps.



N9. 7l4,226. Y P'a tented-Nov. 25', I902.

W. H. NURTHALL.

COIL FOR ABC LAMPS.

(Application filed May 1, 1902.)

(No Model.)

WITNESSES: 8 //v VENTOH W W 6 William H.North.11 By a I m THE unnms PETERS co. mo'roun-mu wnsm mcm, n. c.

UNITED STATES PATENT OFFICE.

WILLIAM H. NORTHALL, OF ELl/VOOD, INDIANA.

COIL FOR ARC-LAM PS.

SPECIFICATION forming part of Letters Patent No. 714,226, dated November 25, 1902.

Application filed May 1, 1902. Serial No. 105,436. (No model.)

To all; whom, it may concern-.-

Be it known that LWILLIAM H. NORTHALL, a citizen of the United States, residing at Elwood, in the county of Madison and State of Indiana, have invented certain new and useful Improvements in Coils for Arc-Lamps, of which the following is a specification.

There are in many electrical appliances constructions where a magnet-coil is subjected to considerable external heat, and as a result after long-continued use the insulation, ordinarily composed of cotton or linen fiber, becomes charred, so as to result in a short circuit. This is especially true of the coils used in arc-lamps, and great difficulty has heretofore been experienced by reason of the short-circuiting of such coils because of the charring of the insulation, resulting from the long-continued heat of the arc. I am well aware that asbestos is well known as an insulating substance; but so far as I am aware it has always heretofore been used in sheet form or loosely-packed fiber and has never been used as an insulating-covering for wire.

The object of my present invention, therefore, is to produce a magnet-coil the wire of the winding of which is insulated by a covering of asbestos, said asbestos being formed into a string which is wrapped about the wire.

The accompanying drawings illustrate my invention.

Figure 1 is a perspective view of an arclamp coil constructed in accordance with my invention. Fig. 2 is a side elevation of a wire insulated in accordance with my invention. Fig. 3 is a similar view of a slightlymodified form, the insulation in this case consisting of a twine or thread composed of a central core of asbestos fiber and an external wrapping of linen or other long-fiber strands, which, however, form but a very small percentage of the total.

In the drawings, 5 indicates an electrical conductor to be used for the winding of a coil, and this conductor is covered by the wrapping of asbestos twine 6, which is preferably formed of a plurality of strands, as

may be used indefinitely without charring and without shortcircuiting. The entire coil may also be brought to a red heat without causing short-circuiting even though the insulation be of the form shown in Fig. 3, for the reason that the vegetable fiber, though becoming charred, forms so small a percentage of the total as not to interfere with the insulation.

I claim as my invention 1. A coil for arc-lamps in which the wirewinding is insulated by a wrapping of asbestos twine composed of fibrous asbestos and a small proportion of tough long fiber.

2. A coil for arc-lamps in which the wire of the winding is insulated by a wrapping consisting of a twine formed of a central core of asbestos and an external wrapping of longfiber twine which forms a comparatively small percentage of the whole.

3. An insulator for wire consisting of a twine formed of asbestos and a small proportion of tough long fiber incorporated therewith, which may be wrapped about the wire.

4. An insulator for wire consisting of a twine formed of a central core of asbestos, and an external binder consisting of longfiber vegetable twine which forms butasmall percentage of the whole.

In witness whereof I have hereunto set my hand and seal, at Elwood, Indiana, this 2d day of April, A. D. 1902.

WILLIAM H. NOR'IHALL. LL. 8.]

Witnesses:

JACOB Looms, A. L. HAPPER. 

